Sintering machine

ABSTRACT

An elongated travelling grate is carried by a Support arrangement which has two transversely spaced rail units supporting the grate for movement along an endless path defined by two upper rail unit portions each having a discharge end, two lower rail unit portions each having a discharge end, two lower rail unit portions, and two at least partly curved connecting portions each of which connects one of the upper and one of the lower rail unit portions at the respective discharge end. Hydraulic pistons or the like engage the connecting portions in the region where the same join with the lower rail unit portions, so as to effect limited displacement of the connecting portions longitudinally of the grate relative to the upper and lower rail unit portions. A buffer arrangement engages the connecting portions intermediate the upper and lower rail unit portions.

United States Patent 11 1 Stanke et al.

1 1 SINTERING MACHINE [75] Inventors: Walter Stanke. Essen; Gottfried Mertens, Kettwig. both of German [73} Assignee: Heinrich Koppers GmbH. Essen.

Germany 122] Filed: Aug. 12, 1974 1211 Appl. No: 497.131

Related US. Application Data [63] Continuationalt-part of Set No, 171.341. Jul 111.

1972. abandoned 1 1 NOV. 11,1975

3.358.981 11/1907 O}|er 4311137 X Pri/nm r Emminer-John J. Camb) .-1!(u)llt' Agenl. 0r FirmMichael S. Striker [57] ABSTRACT An elongated travelling grate is carried by a Support arrangement which has two transversely spaced rail units supporting the grate for movement along an endless path defined by two upper rail unit portions each having a discharge end. two lower rail unit portions each having a discharge end. two lower rail unit portions. and two at least part]; curved connecting portions each ol which connects one of the upper and one of the lower rail unit portions at the respective discharge cnd. Hydraulic pistons or the like engage the connecting portions in the region where the same join with the lower rail unit portions. so as to effect limited displacement of the connecting portions longitudinally of the grate relative to the upper and lower rail unit portions. A buffer arrangement engages the connecting portions intermediate the upper and lower rail unit portions.

10 Claims, 6 Drawing Figures US. Patent Nov. 11, 1975 Sheet 2 of6 3,918,894

Fig.2

US. Patent Nov. 11, 1975 Q Sheet 3 of6 3,918,894

US. Patent Nov.11, 1975 Sheet50f6 3,918,894

US. Patent Nov. 11, 1975 Sheet6 of6 3,918,894

SINTERING MACHINE CROSS REFERENCE TO RELATED APPLICATION This is a continuationdn-part of our related copending application Ser. No. 271.343. filed July ll]. 1972. now abandoned.

BACKGROUND OF THE INVENTION The present invention relates generally to sintering machines, and more particularly to a sintering machine having an arrangement for varying the path length in which a travelling grate of the machine moves.

It is already known from the prior art to provide sintering machines in which a grate travels in an endless path. the grate usually being provided of a plurality of pallets. The path has an upper and a lower path portion, and these are connected by a curved connecting portion. with the pallets of the grate being discharged from the upper rail unit portion to travel around the curved connecting portion and to return to the upstream end of the upper rail unit portion via the lower rail unit portion. In a sintering machine the pallets which together make up the travelling grate are of course heated and the thermal expansion of these pallets in the direction of travel is one factor which has been giving trouble. Another is that wear of the pallets over a period of time can also result in a change of the longitudinal dimensions of the respective pallets. In either case. entry of the pallets into the curved connecting portion encounters difficulties if an insufficient safety gap between the first pallet of the continuous chain of pallets (i.e., the travelling grate) and the last pallet of the chain, that is between the pallet which is still in the upper rail unit portion and the one which is already in the curved connecting portion, must be maintained. Furthermorefthe pallets must not impinge with too great a force upon one another as each pallet is discharged at the discharge end of the upper rail unit portion and travels around the curved connecting portion to impinge upon the pallet which is ahead of it.

The problems which have here been outlined are not new, and it has already been appreciated that measures are required to overcome them. The prior art proposes to make the curved connecting portion displaceable in the longitudinal direction of the upper and lower rail unit portions, that is in the longitudinal direction of the travelling grid. For this purpose the upstream end of the curved connection portion, that is the end which joins with the discharge end of the upper rail unit portion, is mounted on rails by means of wheels, and is connected with a counterweight which exerts upon it a force in directing towards the stationary components of the machine. However, difficulties have been encountered with this prior-art proposal in that it does not guarantee that the curved connecting portions will be displaced in parallelism with the longitudinal axis of the travelling grate, a requirement which is a prerequisite for the parallel displacement of the pallets which make up the travelling grid.

SUMMARY OF THE INVENTION It is. accordingly. a general object of the present invention to overcome the disadvantages of the prior art.

More particularly. it is an object of the present invention to provide an improved sintering machine in which these disadvantages are avoided.

Another object of the invention is to provide such improved sintering machine which is relatively simple in its contruction and reliable in its operation insofar as the features of the invention are concerned.

In pursuance of these objects. and of others which will become apparent hereafter. one feature of the invention resides in a sintering machine. which. briefly stated, comprises a combination including an elongated travelling grid having a plurality of pallet means. and support means including two transversely spaced rail units supporting the grid for movement along an endless path defined by two upper rail unit portions each having a discharge end. two lower rail unit portions. and two at least partly curved connecting portions each connecting one of the upper and one of the lower rail unit portions at the respective discharge end. The travelling grid advances in one direction along the upper rail unit portions toward the discharge ends for travel via the connecting portions to the lower rail unit portions. Displacing means engages the connecting portions in the region of the juncture of the same with the lower rail unit portions. for effecting limited displacement of the connecting portions in longitudinal direction of the grate relative to the upper and lower rail unit portions. Buffer means engages the connecting portions in the region between the juncture of the connecting portions with the upper rail unit portions and substantially the midpoint between the upper and lower rail unit portions.

Thus it will be seen that the actual displacement of the connecting portions in a sense lengthening or shortening the path is effected by the displacing means, that is by mechanical means provided for this purpose. The mechanical means provided at both sides of the apparatus, that is at both rail unit portions. are advantageously provided with a common drive so that it is assured that both curved connecting portions are displaced simultaneously and identically.

The displacing means can be provided in form of screw spindle arrangements, toothed racks, levers or the like. If screw spindle drives are used, they can be driven by a common worm drive motor, with appropriate couplings and angle drives being interposed for motion transmitting purposes. This is particularly advantageous if subsequent operations require that a correction of the position of one of the curved connection portions with reference to the other (i.e., not displacement of both simultaneously) is required, because this can be carried out in a simple manner by simply uncoupling the spindle associated with the connecting portion to be moved, effecting the necessary movement. and establishing the connection again by engaging the coupling means. The spindle driven or the like can for instance be mounted on the supporting frame of the machine or another suitable component, so that they themselves cannot become displaced relative to other components.

The buffer means also can be provided in various different forms, for instance in form of hydraulic cylinders, springs, counterweights or the like. It will be employed substantially between the midpoint or the connecting portions intermediate the upper and lower rail unit portions, and the point where the connecting portions are connected with the upper rail units portions. lf hydraulic cylinders are used for the purpose, then two of them are provided. each associated with one of the curved connecting portions and being connected hydraulically with one another and also with a hydraulic reser\ oir. The pressure oil accomodated in the reser- \oir and acting upon the hydraulic cylinders exerts to a permanent force upon the can ed connecting portions. and depending upon the position of the connecting portions and the oil volume present in the reservoir in de pendence upon this position. the forces exerted by the hydraulic cylinders may vary within narrow limits. They correspond to the load forces. which are reaction forces caused by the movement ofthe pallets along the curved connecting portions. The magnitude of these reaction forces differs. depending upon the impingement of the individual pallets with one another.

Because the magnitude can differ as pointed out abmc. the invention proposes to overcome disadvantageous effects of this by providing the connecting conduit between the two hydraulic cylinders and the hy' draulic resenoir with a throttling element (known per set which throttles the flow of oil.

It is also important that provision be made for circumstances where the sintering machine be subjected to one-sided temperature fluctuations. because possible length variations in the frame of the apparatus due to thermal influences and thermal fluctuations. for in stance as a result of radiation from an adjacent sintering machine or as a result of contact by cold air. will not be prevented due to the presence of the throttling device. since such variations take longer periods of time and will be compensated-for by the two hydraulic cylinders without influencing the position of the curved connecting portions with respect to the upper and lower rail unit portions. The invention further provides. in accordance with another concept. a conduit sur rounding the throttling element. with this conduit being provided with a closure element which opens when the displacing means is activated. The end positions of the curved connecting portions. that is the opposite positions which can be reached by the curved connecting portions upon maximum displacement of the same in one or the opposite direction. can be controlled by limit switches acting upon the displacing means to terminate operation of the same when the respective end position is reached.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself. however. both as to its construction and its method of operation. together with additional objects and advantages thereof. will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is a side view. in a fragmentary detail. of the discharge end of a sintering machine incorporating the present invention;

FIG. 2 is a section taken on line lI-ll of FIG. 1;

FIG. 3 is a sectional view. illustrating a detail of FIG. I on an enlarged scale;

FIG. 4 is a schematic of the hydraulic system for the buffer means of FIG. I;

FIG. 5 is a view similar to FIG. I. but illustrating a somewhat different embodiment; and

FIG. 6 is also similar to FIG. I. illustrating still an other embodiment of the invention.

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DFSCRIPIION OF THE PREFERRED EMBODllvlFNTS Discussing the drawing in detail it will be seen that the discharge end section of the sintering machine. which latter is not identified in detail because it is known per se from the art. is designated with reference numeral I in toto. It may for instance be supported on antifriction bearings 2 on supports 3 on which it is displaceable in the longitudinal direction of the sintering machine. as indicated by the arrow 4. The purpose of such displacement is to make it possible to vary the gap 5 between the pallets 6 and 6' as the latter enter into the curved connecting portions 7. It will be appreciated from a reference to FIG. 2 that the sintcring machine has two transversely spaced rail units each having an upper and a lower longitudinal rail unit portion and at the discharge end which is shown in FIG. I and designated with reference numeral 1, the respective curved connecting portion 7 connecting the upper and lower rail unit portions.

When the discharge end section I is to be displaced longitudinally in the direction of the arrow 4, that is in the direction in which the grate composed ofthe pallets 6. 6' travels (the direction of travel is indicated in FIG. I with the arrow X) the displacing means provided for this purpose are operated. In the illustrated embodiment such displacing means is in form of two self retarding screw spindle elements 8 which are located at the opposite sides of the sintering machine. being connected to the stationary portion 9 thereof beneath the lower run 10. and being engaged at II with the dis charge end. The elements 8 are connected via shafts 12. 12a angle drives I3 and couplings 14 with a worm drive motor 15 which acts upon both of them. so that the displacement of the curved connecting portions 7 at both sides of the discharge end I in unison and by identical distances is assured. If one of the connecting portions needs to be adjusted with reference to the other, it is a simple matter to disengage one of the shafts I2 to permit such displacement and then to reengage the coupling.

Details of the above construction are shown in FIG. 3. which is a vertical section through the arrangement that is illustrated in FIG. I. The shaft 12 is a hollow shaft which is provided with flanges 3 I. 32 at its upper and lower ends. respectively. Flange 3] has a plurality ofcircumferentially spaced bores 33. and flange 32 has similar bores 34. The worm drive motor 15 has a rotary shaft 38, a flange 37 of which is provided with projections which extend into the respective bores 33. although this relationship could evidently be reversed. Similarly. the hollow shaft 40 which is carried by the housing (not shown) of the spindle element 8. is provided with a flange 39 having projections 36 which extend into the bores 34; this relationship of bores and projections could evidently also be reversed. The flanges 31 and 37 are vertically spaced from one another by a distance 4| which is greater than the length 42 (in vertical direction) of the projections 36.

This arrangement makes it possible to raise the shaft 12 until the projections 36 disengage from the bore 34, thereby uncoupling the spindle element 8 from the motor I5. When this is done at the arrangement at one side of the machine. energization of the motor I5 will cause only the other arrangement to be operated. whereby adjustment of the connecting portions relative to one another can be effected. Since the shafts I2 are relatively light weight. the uncoupling and coupling can be carried out by hand. simply by raising or lowering the respective shaft 12.

The screw spindle elements are displaceable between two end positions; i.e.. a farthest-left position and a farthest-right position in FIG. 1. To provide a position control over this displacement. limit switches 48., 49 of known construction may be stationarily mounted on the machine base. frame. or the like. being spaced from one another in the direction of displacement 4 of the spindle elements 8. The portion In of the discharge and section I. which is connected with the spindle elements 8 to be displayed by the same. may carry a pin or other projection 50 which moves with the portion Ia and. depending upon the direction of movement of the portion In. engages and operates the switch 48 or the switch 4). ln known manner (this type of arrangement is widely used in many industries) the switches 48, 49 are connected with the power-supply circuit of the motor 15. so that this circuit is interrupted and the motor stopped. when either of the switches 48. 49 is operated by engagement with the projections 50. Evidently the switches could be located on the portion In. and the projection 50 on the base.

Located below the upper run I6. which is of course the upper rail unit portion. and again at both lateral sides of the stationary portion of the sintering machine. there are buffer means here illustrated as hydraulic cylinders 17. These cylinders have pistons 18 which are connected with the discharge end 1 at 19. They serve as elastic buffers to provide for a compensation of possible length variations resulting from temperature differentials that may exist between the left and right-hand side of the discharge end. without influencing the con figuration of the curved connecting portions 7.

A hydraulic circuit for operating the cylinders 17 is shown in somewhat simplified form in FIG. 4. The two cylinders 17 with their respective pistons I8 are shown diagramatically in FIG. 4. The hydraulic pressure tank 51 accomodates in its interior a cushion or bubble 52 of gas. such as nitrogen or the like. which exerts a substantially constant pressure upon the hydraulic fluid 53 from which it is separated by a flexible diaphragm 51a or the like, and thus upon all the fluid that is active in the system. If this pressure drops. for example because of fluid-losses due to leakage. the pressure-responsive switch 54 energizes pump 55 which pumps additional fluid into the system, out of the reservoir 60. A second pressure-responsive switch 56 is set to respond when the pressure is returned to its predetermined level, by de-encrgizing the pump 55. An adjustable throttle 57 is interposed in the conduit connecting the tank SI with the cylinders 17, and a by-pass line 58 bypasses the throttle 57 and has interposed in it a magnetic valve 59 which is operated when the arrangement for displacing the end section 1 is being used. Reference numeral 61 identifies a safety valve which opens to relieve pressure in the event the pressure in the system should exceed the permissable upper limit.

FIG. 5 is identical with FIG. 1, except that the cylinders l7 and pistons 18 are replaced with a mechanical buffer arrangement. in form of springs 43 (one shown) which are located at the opposite sides of the machine and act between the end section I and the stationary portion 9 of the machine.

FIG. 6, finally. is also identical with FIG. I but shows another type of mechanical buffer arrangement which replaces the cylinders 17 and pistons 18. The arrangement in FIG. 6 uses a counterweight 44 which depends from a rope. chain or a similar element 45. The latter is guided about a freely turnable roller that is mounted on the end section I for movement with the same. The free end of the element 45 is fixedly connected at 47 to the stationary machine portion 9. The operation of this arrangement is self evident It is evident that the invention provides for a two-fold adjustment of the end section I. The use of the spindle elements 8 which are located at the lower region of the machine permits an intentional and selectable mechanical displacement of the end section 1 relative to the stationary portion 9. The respective buffer arrange ments which are located in a middle or upper region of the machine. provide on the other hand for an auto' matic compensation of the upper portion of the end section I relative to the stationary portion 9. for example if temperature differentials exist between the lefthand side and the right-hand side of the end section 1. resulting in differential thermal expansion or contraction of these sides of the end section 1 in the middle or upper regions thereof.

It will be appreciated that the present in\ention achieves its stated objections in an efficient and reliable manner, and in a manner which is rather simple and can be incorporated not only in new but also in existing sintering machines of the type under discussion.

It will be understood that each of the elements described above. or two or more together. may also find a useful application in other types of constructions differing from the types described above.

While the invention has been illustrated and described as embodied in a sintering machine. it is not intended to be limited to the details shown. since various modifications and structural changes may be made without departing in any way from the spirit ofthe present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that. from the standpoint of prior art. fairly constitute essential characteristics of the generic or specific aspects of this invention and. therefore. such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

I. In a sintcring machine. a combination comprising an elongated travelling grate having a plurality of pallet means; support means including two transversely spaced rail units supporting said grate for movement along an endless path defined by two upper rail unit portions each having a discharge end. two lower rail unit portions. and two at least partly curved connecting rail portions each forming a juncture with one of said upper and one of said lower rail unit portions at the respective discharge end, said travelling grate advancing in one direction along said upper rail unit portions towards said discharge ends for travel via said connecting portions to said lower rail unit portions; displacing means engaging said connecting portions in the region of the juncture ofthe same with said lower rail unit portions. for effecting limited displacement of said con necting portions in longitudinal direction of said grate relative to said upper and lower unit portions; and two buffer means each engaging said connecting portions in the region adjacent said upper rail unit portions.

2. A combination as defined in claim I. said displacing means comprising displacing elements each engaging one of said connecting portions. and a dri\e common to said displacing elements,

3. A combination as defined in claim 2. wherein said displacing elements are screw-spindles.

4. A combination as defined in claim 2. wherein said buffer means comprises h draulic cylinder-and-piston units.

5. A combination as defined in claim 2. wherein said butler means comprises spring elements 6. A combination as defined in claim 2, wherein said buffer means comprises counter eights.

7. A combination as defined in claim 4, siad buffer means comprising at least two of said hydraulic c \linder-and-piston units each engaging one of said connecting portions. a fluid-rervoir. and conduit means connecting said h draulic units with one another and ltl 8 also connecting said h draulic units with said fluidreservoir.

8. A combination as del'ined in claim 7: and further comprising throttling means interposed in said conduit means 9. A combination as delined in claim 2; further comprising individual coupling means coupling each of said displacing elements individually and rcleasabl with said dri\c,

It). A combination as defined in claim 2. said displacing elements each being displaceable between two ter minal positions; and further comprising limit switch mcahs operativel associated with said drive and said displacing elements for terminating operation oi the former in response to reaching of a respective terminal position b the latter. 

1. In a sintering machine, a combination comprising an elongated travelling grate having a plurality of pallet means; support means including two transversely spaced rail units supporting said grate for movement along an endless path defined by two upper rail unit portions each having a discharge end, two lower rail unit portions, and two at least partly curved connecting rail portions each forming a juncture with one of said upper and one of said lower rail unit portions at the respective discharge end, said travelling grate advancing in one direction along said upper rail unit portions towards said discharge ends for travel via said connecting portions to said lower rail unit portions; displacing means engaging said connecting portions in the region of the juncture of the same with said lower rail unit portions, for effecting limited displacement of said connecting portions in longitudinal direction of said grate relative to said upper and lower unit portions; and two buffer means each engaging said connecting portions in the region adjacent said upper rail unit portions.
 2. A combination as defined in claim 1, said displacing means comprising displacing elements each engaging one of said connecting portions, and a drive common to said displacing elements.
 3. A combination as defined in claim 2, wherein said displacing elements are screw-spindles.
 4. A combination as defined in claim 2, wherein said buffer means comprises hydraulic cylinder-and-piston units.
 5. A combination as defined in claim 2, wherein said buffer means comprises spring elements.
 6. A combination as defined in claim 2, wherein said buffer means comprises counterweights.
 7. A combination as defined in claim 4, siad buffer means comprising at least two of said hydraulic cylinder-and-piston units each engaging one of said connecting portions, a fluid-rervoir, and conduit means connecting said hydraulic units with one another and also connecting said hydraulic units with said fluid-reservoir.
 8. A combination as defined in claim 7; and further comprising throttling means interposed in said conduit means.
 9. A combination as defined in claim 2; further comprising individual coupling means coupling each of said displacing elements individually and releasably with said drive.
 10. A combination as defined in claim 2, said displacing elements each being displaceable between two terminal positions; and further comprising limit switch means operatively associated with said drive and said displacing elements for terminating operation of the former in response to reaching of a respective terminal position by the latter. 